1. Field of the Invention
The present invention relates to a magnetic recording medium and more particularly a high-density magnetic recording medium, which is required to have high storage stability, having a low surface resistivity.
2. Description of the Related Art
Low surface resistivity is particularly necessary for high-density magnetic recording media which are required to have long-term storage stability and reliability, such as magnetic tapes for computers.
Reduction of surface resistivity could easily be achieved by increasing the amount of carbon black, but a mere increase in the amount of carbon black causes deterioration of surface smoothness and electromagnetic conversion characteristics, thereby resulting in poor properties of the coating film, such as formation of streak lines.
In addition, a coating composition containing an increased amount of carbon black changes its characteristics during a coating operation, the coated film thus evincing film shows an increase in surface resistivity with time from the start to the end of the coating operation so that the resulting coated film has an unstable surface resistivity.
This is ascribable to structural change in the coating composition with time after addition of a hardener.